1. Field of the Invention
The invention relates to an air conditioner capable of reducing noise produced during rotation of a cross flow fan thereof.
2. Description of the Conventional Art
FIGS. 6 to 9 are diagrams showing a conventional air conditioner disclosed in, e.g., Japanese Patent Unexamined Publication Hei-3-31624/(1991).
In these figures, reference numeral 1 designates an air conditioner body, which is a wall type; 2, a heat exchanger disposed within the air conditioner body 1; and 3, a cross flow fan disposed in parallel to the heat exchanger 2 inside the body 1. The air conditioner body 1 draws air from a room into an inlet 4 by rotation of the cross flow fan 3, exchanger heat with the air by passing the air through the heat exchanger 2, and blows the heat-exchanged air out into the room from an outlet 5. The heat exchanger 2 includes a plurality of juxtaposed fins 6 and coolant pipes 7 passing through the plurality of fins 6. The drawn in air threads its way through the coolant pipes 7 among the plurality of juxtaposed fins 6. On an edge portion of the fin 6 closest to the cross flow fan 3 is a bent portion 6a formed by pressing the same portion to right and left in a planar direction of the fin 6 as shown in FIG. 7.
The operation of the air conditioner will be described next. The air drawn from the inlet 4 by the rotation of the cross flow fan 3 enters into the cross flow fan 3 after passing through the heat exchanger 2. A vortex 8 such as shown in FIG. 8 is produced on the downstream side of each coolant pipe 7. As a result, the wind speed of the air immediately after the heat exchanger 2 drops locally at each vortex 8 as shown in FIG. 9. When the vortex 8, which marks a local drop in the wind speed, has entered the cross flow fan 3, there is a change in lift generated at each blade of the cross flow fan 3 which causes pressure pulsation, which in turn causes noise during rotation of the cross flow fan (the noise being a component whose frequency f=n.times.N.times.Z, where n is an integer and N is the number of blades).
However, since the conventional air conditioner has the bent portion 6a on the fan 6, the air 9 flowing through the bent portion 6a goes behind the coolant pipe 7, suppressing the vortexes 8 adjacent to the bent portion 6a. This causes a length L of each vortex 8 to be reduced to La, impeding the vortexes 8 from entering into the cross flow fan 3. As a result, the noise during the rotation of the cross flow fan 3 can be reduced.
To reduce the noise during the rotation of the cross flow fan 3 in the thus constructed air conditioner, the heat exchanger 2 and the cross flow fan 3 must be separated by at least a distance La, which is the length of the reduced vortex 8. Therefore, such a distance has been the smallest possible distance between the heat exchanger 2 and the cross flow fan 3 to make the air conditioner thin. Making an air conditioner thinner by putting both components 2, 3 closer to each other by a distance smaller than the above-noted distance aggravates the noise during the rotation of the cross flow fan 3.